The invention relates to a live roller conveyor comprising a plurality of rollers driven by friction drive from a main drive shaft wherein at least some of said rollers are driven from the main drive shaft through a secondary drive shaft and there being control means to vary and/or remove the torque transmitted between the main drive shaft and the secondary drive shaft.
For example, when articles are accumulated on such a conveyor by adjustment of a drive force, and/or by engagement with an arresting means at an arresting station, an undesirably high end load on the article and/or the arresting means may be avoided. Such a live roller conveyor is disclosed in GB-B-2,286,572.
An object of the present invention is to provide such a live roller conveyor in which the control means for adjusting and/or removing the drive force is improved.
According to the present invention we provide a live roller conveyor comprising a plurality of rollers driven by friction drive from a main drive shaft wherein at least some of said rollers are driven from the main drive shaft through a secondary drive shaft and there being control means to vary the torque transmitted between the main drive shaft and the secondary drive shaft, wherein the main drive shaft is disposed within the secondary drive shaft, said secondary drive shaft being movable relative to the main drive shaft so as to vary torque transmitting frictional engagement therebetween.
The secondary drive shaft may be displaced out of driving engagement with the main drive shaft by movement of the secondary drive shaft in a downward direction transversely relative to the main drive shaft.
The secondary drive shaft may be moved relative to the main drive shaft by a control means.
Said movement of the secondary drive shaft may be as a result of engagement of the secondary drive shaft by an actuating member of the control means.
The control means may comprise a support and said actuating member may be movable relative to said support.
The support may comprise bearings which engage the main drive shaft.
Limit means may be provided to limit movement of the secondary drive shaft relative to the main drive shaft.
The limit means comprise a stop member fixed relative to the support and engageable by the secondary drive shaft to limit movement thereof relative to the main drive shaft.
The stop member may have a surface engagable by the secondary drive shaft which is part-circular and concentric with the longitudinal axis of the main drive shaft.
Where the support means comprises bearings, the stop means may be held generally concentric with said main drive shaft by virtue of the engagement of the bearings with the main drive shaft.
The limit means may alternatively comprise means to limit movement of the actuating member.
According to a first embodiment of the invention, the control means may be carried on the main drive shaft.
The control means may be prevented from rotation with the main drive shaft.
The control means may be prevented from rotation with the main drive shaft by engagement of a portion of the control means with a frame member on which the main drive shaft and the rollers are rotatably carried.
The support means may engage said frame member.
The frame member may extend generally parallel to the longitudinal axis of the main drive shaft.
Alternatively the frame member may extend transversely to the longitudinal axis of the main drive and the control means may be movably attached to said frame member.
The control means may be movably attached to said transverse member by bolts received in apertures in the control means, said apertures having a larger diameter than said bolts.
It will be apparent that bolts could alternatively be provided on the control means received in apertures in the transverse member.
Where the conveyor comprises a frame, in a second embodiment of the invention the control means may be fixed relative to the frame.
Where the frame comprises a member transverse to the longitudinal axis of the main drive shaft, the support may be fixed to said transverse member.
According to a first alternative of said second embodiment of the invention, said bearings may support the main drive shaft.
According to a second alternative of said second embodiment of the invention or to the first embodiment of the invention, the conveyor may comprise a further bearing wherein the main drive shaft is supported in said further bearing.
Said further bearing may be a self aligning bearing.
Where the conveyor comprises a frame having a transverse member, said further bearing may be fixed to said transverse member.
In either embodiment of the invention, the actuating member may be driven by an actuating means of the control means.
The actuating means may comprise a fluid operated cylinder or a solenoid.
Movement of the actuating member may be limited either directly or indirectly by limiting movement of the lever of the actuating means.
The actuating means may be carried on said support.
The actuating member may be driven by the actuating means through a lever pivotally connected to the support, particularly when the actuating means is a solenoid.
The actuating member may alternatively be driven by the actuating means by virtue of the actuating means acting directly on the actuating member, particularly when the actuating means is fluid operated.
The actuating member may comprise an end part of, or an element attached to, a piston of a fluid operated actuating means.
The secondary drive shaft may be moved relative to the main drive shaft by two control means disposed at longitudinally spaced positions of the secondary drive shaft.
Said longitudinally spaced positions may be adjacent opposite ends of the secondary drive shaft.
The secondary drive shaft may be movable between a position in which the axes of rotation of the drive shafts are mutually offset and a position in which the axes are coaxial or substantially coaxial to vary the frictional torque transmission therebetween.
The roller may be rotatably mounted on a frame so as to extend generally transversely to the direction of advance of an article to be conveyed thereby whilst the main drive shaft is also mounted on the frame but in a direction so as to extend generally longitudinally of said direction of advance of the articles.
The friction drive means for at least some of said rollers may comprise an elastomeric belt engaged with a roller and with the secondary drive shaft either directly or through an intermediate member which is frictionally rotatably mounted on the secondary drive shaft.
The live roller conveyor may comprise others of said plurality of rollers which are driven from the main drive shaft by a friction drive means which comprises an elastomeric belt engaged with each of such other rollers and with the main drive shaft either directly or though an intermediate member fictionally rotatably mounted on the main drive shaft.
The secondary drive shaft may comprise further alignment means.
The further alignment means may comprise a disc attached to said secondary drive shaft and extending transversely to the longitudinal axis thereof, said disc being receiving in bearings attached relative to a frame of the conveyor.